Two-stage hydraulic pressure pump



y 1952 B. BEAMAN ETAL 2,604,047

TWO-STAGE; HYDRAULIC PRESSURE PUMP Filed Sept. 19, 1945 4 Sheets-Sheet 2 J5 .1? g I .5'0 78 7 z; 70 6 F; 74 F- 13 0 g 1 2; 7 Z4 'J I I 5:

y 1952 B. BEAMAN ETYAL 2,604,047

TWO-STAGE HYDRAULIC PRESSURE PUMP Filed Sept. 19, 1945 I 4 Sheets-Sheet 3 INVENTORS. Berna rd Badman,

.- S 1 a t er b ect is under the force or internal pressure bore; e ds oti' hemu pianii ip ov de z-valve for'csujchgm s'sure tosmaintainf' :sired. value rsomewh t lo er: than, th Pressur ,in the. outle of theaphm xd ired'hr s -aj z r additional object is to provide a Patented July 22, 1952 NI ST TE TWO-STAGE HYDRAULIC, PaEssUaE PUMP Bernard Beaman, Julius Hulma'n, and Robert a v Stein, Dayton, Ohio; saidfBeaman and said Stein assignors to said Hulman Application September 19, 1945', Serial No. 617,424 g (01.103 5) (Granted under the" act of )March 3, 1883, as

13 Claims.

7 amended April 30, 1928; 370 O. G. '757)" I The invention described herein rna y be manui-actured and usedby or for the Government for governmental purposes without the payment'to usof any royalty thereon. I ,qOur' present invention is related in subject matter to our co-pending applications, Serial No. 1532,36. filed March 12, 1945, now Patent No. 2359336 of January 25, 1949, and Serial No. 598,356 filed June 8, 1945, now Patent No. 2,495,685 of January 31, 1950, and, in generalis 'a hydraulic pressure pumpof two-stage character which" is designed for efiicient operation at extremely high pressures in the second. stage, ;O Ile objectofthe inventi'o'n' is to provide a two-stage pump which is compact in designjand simple oi construction; involving but few; parts which can be readily fabricatedand assembled.

, Another object is to provide] a pump wherein I. relief means from the outlet of the vanepump'to loade dbearings are mininiize'dfthe thrust forces lheing talgen hy stationary thrustsur faces an'dia halll bearing arrangement being provided be- ,tween a uca'm face and the pistohs of the high pr r m w Still another object isf to: provide a pump wherein" effective seals against fluid loss are "pro- ,vided in a simple manner."

A furtherobject is to provide a iirst stage pump of sliding vane type and'a second-stage pump, cornprisinga rotatable barrel having cylinder bores therein with pistons providedin 'thebores-and slidable under theaction of a cam,

t e ertinaarran men l r i is inlet bf h excess capacity of the vanepump into the'body pump to v the lowpressure pump section and then in bu s ori di t sm m izi atil b lence and conduit frictio i iieia vaoa the effectively seats against a valveplate o t v housin a d acting impar all le without-exceeding such to; the high pressure pump sectionand: to {.11 the outlet being comparatively direct andcoverbar;re l .o f, the high pressure pump so thatit t o-stag e pump wherein the mechanism of twospurnp iin the inlet thereof to thus maintain ,a predeterrmined charging pressurefor the piston pump which forces the pistons against the cam with out "the necessity of providing return springs,

linkage orsorne other mechanical rneansj for this purpose. a jStill another additional object is'to provide a'structure which canbe rotated injone direction for pumping liquid, and can be readily adjusted Vfor rotationih the opposite. direction by turning an end plate a'nd'a valve, plate through or 'movement. v f

,A further additional object is to bleed the of the piston or main 'purnp throughthe' relief valve whereby the by-p-assed liquid, provides" a circulatin cooling fluid for "redfucing the temperaturejrise "oi the pump and, to provide a lowered operating temperature. within the pump. Still a further additional object is to provide a vnovel ball bearing arrangement between a creep plateand a carnwhich is designed to reduce contactpressure appreciably and tofprovide ,eX- tremely' high thrust forcesas' found necessary when pumping liquid at extremely highlpre'ssure, such? as three" thousand pounds per squareinch.

Other additional objects are toprovidea modifled structure .whereina cam plate may be adgushed asifto inclination for changing the degree [of reciprocation of 'pumpjplilngers and to provide a means forrautornatically. adjusting'the DQSitioh thecampl atf fliveredbythe p m 1' e A lw i e a d th i h ii V w 'ren iqn cqesis in e aicohrstructioa a ,v U

mam-s ds ombina i fih var e l s-9 areeWeieB Qe' h rei e'fli' amo -s t'i h pointed: out incur claims illustrated I in he meidr win a wher n: si fr ntelev on a r uma. s: Fi -2 i wea l a z e eo 1.4;;

response o'th'e pressure ev r deviceg wherebyr the, c bjectsl contemplated Fig, 3 is vertical sectional view on the line 3-3 of Fig. 2;

Fig. 4 is a sectional view on the line 44 of Fig. 2 showing a relief valve between the outlet and the inlet of the low pressure pump;

Fig. 5 is a sectional view on the line 5-5 of Fig. 2;

Fig. 6 is a sectional view on the line 6--6 of Fig. 5 showing the end of the pump housing and the ported end of the high pressure cylinder barrel therein;

Fig. 7 is asectional view on the line l-'I of Fig. 5 showing the low pressure pump and a portion of the porting arrangement;

Fig. 8 is a sectional view on the line 88 of Fig. 5 showing a rear elevation of the valve plate between the low pressure pump and the,

high pressure pump and the porting arrangein the end plate I8 and the sleeve '34 is retained in the cam 24. Loosely splined at 42 on the barrel drive shaft 36 is a barrel 44 having a flatsealing face 50 to contact with a flat sealing face 52 of the valve plate I6. The loose splining of the barrel 44 to the shaft 36 permits ready corisure acting on the cylinder bore ends surroundment therethrough;

Fig. 9 is asectional view on the line 9-9 of Fig. 5 showing the front view of the valve plate Fig. 10 is a sectional view on the line Ill-I0 of Fig. 5 showing a front view of the rear end plate of the pump and a frontview of the stator] and rotor of the low pressure pump;

Fig. 11 is a sectional view similar to a portion of Fig. 3 showing a modified bearing construction for the cam and creep plate;

' Fig. 11a is aface view of a creep plate shown sectional view on the reciprocatory strokes of the pistons in the high P p mp; 13 is a'sectional view on the line 'I3-I3 of Fig. 12 showing detail of construction of the modified form of our invention shown in Fig.

12; and

' Fig. l4 is asectional view of pressure responsive'regulating means for the 'cam'plateof Fig.125'

f On the accompanying drawings we have used 1 the reference numeral III to indicate a cylindrical pump housing. The housing II] has an end plate IZ' at its front end which constitutes a mounting flange for mounting the housing, for instance, on an aircraft engine. For mounting 'purposes, bolts or screws may extend through perforations of the flange I2 and thread into thesupporting surface.

of a modified form A valve plate I5 is mounted onthe back end of "the housing and a rear end plate I8 is mounted against the valve plate, as by cap'screws'20,

with asuitable asket or sealing compound between the parts I0, I6iand I8. A cam 24 is mounted the-housing I0 and is retained against rotation'relativethereto by a key] 25 "(see Fig. 3). The cam ispositioned next to the endplate I2, and the end platejitself is"retained' in position-as by cap screws I5. The'cam 24'has' abearing race 26 receiving ballbearings fl', and

thelballs' interfitl with ase'con'd race 28' of a creep plate3n of washer like character," The groove 26' followsthe path of'a truncated cylinend plate I8. r 4

ing the ports 58. The cylinder bores 54 and the pistons 56 constitute a high pressure pump. During starting of the pump, when pressure has not yet built up, it is desirable to make sure ,7 that the faces 50 and 52 are in contact. This may be accomplished by a light spring 59 interposed between the shoulder on the shaft 36 formed by the splining '42 and the barrel shoulder 46, as shown in Figs. 3 and 5.

A low pressure pump is provided in the form of a rotor 38 located within a stator bore 60 of a ring-like stator BI. The stator fits in a bore 62 of the end plate I8. The stator and its bore are eccentric with relation to the axis of rotation, and the rotor is formed on or secured to thebarrel drive shaft 36. The rotor 38 has substantiall radial slots '46 in which vanes 48 are slidably mounted, as shown in Fig.7. The eccentricity of the stator bore 60 effects inward and outward movement of the vanes 48' upon rotation of the rotor 38.

A low pressure inlet boss II is provided on the end plate I8, as shown in Figs. ;2 and 5;-' This;

boss communicate by means of "a passageway I2 with an inlet port I3 of the low pressure pump. Theinlet port is provided in the end plate I8. A low pressure outlet port I5, of similar shape, is provided in the rear face of the-valve plate I6, and the front face'of the valve plate'has an arcuate' high pressurev inlet port 11 for the high the pump. The passageway" B I, at its intake'end,

is reduced, as indicatedatflli, anda sealing ring?!) surrounds the joint to effect a seal from the passageway 8U toythe passageway 8,I between the contacting faces pr the valve plate- I6 and the From the description just made of the passageways and port it will be obvious that the oil or other liquid being pumped can be traced in'a cricuit through thejfollowing elements-z II, I2, '13,.low pressure or vane pump; I5, I6, 11,

high pressure or piston pump- 19.80, I4; 8! and '62." arrangement produces a direct passage of the oil from the -rear of the pump through the end plate'IB and the Iv'alve 'plat e' I6, and then-intothe bari el 44, with adirec't return from the barrel through the-valve plate fl and the end plate I8.- Thus turbulence is minimized, and, -likewise,

'l umpand the interior'oif. the hcusln' selectively; Within the sleeve l 60"is l' which is moved toward -'the -right ini-Fi'g; 4

by the legends HI and LO-in Fig. 2. V

Adrive shaft H is provided having a splined end Hf-for c'onnectionto a power take-oifshaft ofanaircraftengine, or any other suitable means to drlve the pump; "The power take-off shaft would include a means to align'the outer." endof the-drive 'shaft H0 for proper operation without binding. The inner end of the drive shaft H0- has a loosely splined connection H2 with the barrel drive shaft 36.

' The drive shaft I III has a flange H t surround ingit. with which a's eal' plate H8 in the iorni or a ring is engageable. A springlzn'is' seatedagainst "an 'inturned' flange I22 of the end plate 12'. The seal plate 1 I8 is sealed relative to the; housing I0 by means of a diaphragm I28 having its" inner edge clamped to theseal'plate' by a spanner'nut 128 and its outer edge clamped between a washer I30 and the cam 24*by the end plate l2: This provides a pressure chamber, in-. dicatecl at I32, inside of the flange I6; A "The inner end of the drive shaft l'lflisseate'd against a shoulder I34 of the barrel drive shaft 36*whichserves merely as a thrust connection, butrn'ormally, when the pump is operating; the

two are'spacedfrom each other. A passageway I36 is '1:n ov-ided through'the center of the barrel drive -shaftthrough which liquid is adapted? to flow after passing through the splined connec-' tions' 42 and H2 and the'bearing s1eeve'3'4. f a f The passageway I36 communicates with-apres sure relief valve in the form oij'a valve plunger 2 seated against a "ring 'lMf'by a spring 1:45, The valve 'plugacts as a piston in'a'sleeve' ldfl whichserves' to guide its sliding movement; The sleeve l'48 has a head I 50 for screwin'g the sleeve into the end plate l8 at ascrew-threaded con-' nection I52," The sleeve Ma has ports [54 com inunicating with an annular groove 1| 56' which, in turnfcommunicat'e by meanslojf a passage way [58 with the low pressure boss HQ The low pressure pump comprising the rotor 38 and the vanes 48 is higher capacity than the high pressure pump comprising the cylinder bores'5'4 an'd'th'e pistons 56. This is for the purpose of assuring full charging of the high pres sure cylinders for reducing voids 'in the liquid and for keepingthe pistonsin'contact with the r w 'a 0-1? j [I J 'j 'lj'o avoid egrcessive build-up" of pressuraand sist's of a-sleeve I60 a boreil62 of-the' endplate t8." There is a=pair-bff annular gr('ioves""l64 and 166 surrounding the sleeve"- F60. and passageways I 168 and llllserve-to communicate these grooves withintthe indentations.3! and with: a line- 39 V hoop a-substantially even' charging pressurelfrom One of 'theg'znaj'or problems infa small compactr highlystressed pump of the character herein-disclosed isahi'ghcontact pressure which exists between the ends of -the.pistons 56and the flat'creep. plate 30... This, heretofore, has largely been alleviated by: the used complicatedshoes or piston rods; or by enlarging: the. piston: ends. However, a cheaper and. more compact. method is to have the pistons worktz'inzs a conformingv spherical seat in the creep; plate. i This islshown in Fig. 11 and 11a wherein the creep plate- 30 has; a. spherical: seat .31 I for eachpiston. Consei duent wear; iszm'aterially reduced by this arrange-- ment... IA..modified form, of creepiplatetflahis shown: in:- Figs; Illrand: 11c and will 1 be. referred to specifically latera herein. i The-peculiarities of motion dueito the inclina-.-. tion of the axis of rotation ofthebarrel-JM and the inclinedzcreep. plate 30.:make' it: essential that thespherical. indentations 3.! :be properly located.- It. isequite.v usual in: pumpsiof. this kind to locate the: center" line through the bearings 21.101 1116- creep plate centered on the. axishof rotationof the barrel 44I-(indicated at 33 in 'Fig.'i3 causes: the contact face of the creep plate ate- 1 0.- tate about a. center. (seepoint.BBlLdispIaced-flom' the: axisof the barrel- The consequentirelative motion of.thepistonzcontact end on the fiat face is: therebyincreased'. Asl'ong. as the plateis flat and sufliciently 1arge",-there.is.litt1e objection exceptl'for'theexcessive motion'and wear:

When providing individual sphericalseats 31-, as in Fig. ll, means must be takento. have. the seat sufliciently large to: insure: piston engagement. throughout 360=of rotation, and 'it must be madewith a; small: radius. to insure sufficient coniormityzto: reduce contact -.pressure=appreciably. This 'is'acconiplished by having the center of rotation.:. ofthe-xcontact surfaces; indicated at 3'lconnecting the contact faces 31 having itsicente'r indicatedby the point Siletfalling on. arr-axially extending center line 4i located at, or, at least, near/the: axis-of rotation 43 of theshaft 36. It will be-noted'th'at'the center linev M is displaced only slightly'from the center line '43 .and the center-of rotation; 33a forilthe: ball's z'l is-some what further displaced from; The creep-plate motion is thereby reduced consid'erably by its axisiof rotationbemg positioned at an optimum position. I l

The creep plate seatscr indentations-31 serve as;a driving'means for the: creep plate and insure that it moves at the same rotativespeed as the cylinder. barrel. The indentations 3| (see. Figs; 11' and 11a); however; .may be replaced with a continuous annular gro0ve 3l'a as shownin Figs. 11b and: l l-cof the cross-sectionshown for the indentations -3:l if it isnot r' desirableto cause rotation. bf the creep plate simultaneously-with with thehigh pressure side o'fthe-low' pressure plunger against the action'of a spring-"l 16; by liquid under thezb'arrelr Such an arrangement as shown distributes'itheiwear around the entire circumference of such groove instead of. localizingfit 5 in the individualindentationsi lnFigsrlz and 13 we show a modified construc= tion" wherein' some of the parts 'correspo'nd to those already described and,- I accordingly; -=bear thesame'reference numerals. The modified construction, however, provides a means whereby-the displacement or volume output of; the high pressure pump per revolution can be varied from almost zero uptothe rated capacity (if-"the pump in infinitesimalincreinents; 7

Z; Constructionally,,the cam plate 24 has been modified by providing it with trunnion bearings I80 journaled-inibearing sleeves I82. The bearingsleeves I82 are retained in lateral bores I8 I- of the housing: Illbyplugs I86. The cam-plate is therebymountedioroscillation on the axis of,

the trunnions I89 from the maximumjtilted position shown inyFig. 12 to a'vertical .or untilted position wherereciprocation of the plungers G by the creep plate 30 is reduced to zero. At any.

intermediate anglethe displacement will be a proportional intermediate value.

Inasmuch as the displacement of the pistons 54 will be a function of the angular position of the creep plate 39, the displacement will vary may. be responsive to amechanical motion or to differential pressure by utilizing linkage of appropriate nature. By way of illustration we show the-creep plate controlled by the pump-discharge pressure. It is "desirable to maintain full displacement .up to. a predetermined'pressure, and then with.infinitesimal'increases in pressure to have the displacement decrease until; at some pressure slightly higher than that at which full displacement occurs, the displacement is zero.

For this purpose'a pair of projections I90 and I92 is formed on the cam. plate 24 at diametrically opposite positions. {The projection I99Lhas a plunger I94 engagingtherewith and sliding in a cylinder 196;: The projection. I92 has a plunger I 9.8, engageditherewilth and sliding ..in a cylinder 209;; The cylinders I96 and 299 are connectedizby' means of passageways 202 with the high pressure outlet 8.I o'f-rthe pump so that theplungers .I9 I and.'I98;are.responsiveto the outlet pressure thereof-,asaunit. V gSpring seats 204' and 206 surround the projection; I92, and spring seats 208 and 2I0 surround the plunger I98.- "A spring 2I2- is:,interposed be-v tween the seats- 206 and 2H] solthat the position which the camplate: 24 assumeslforanygiven pressure, conditiohwill be a function of the .force of .the springs 2 I 2. the force of oil pressure on the plunger I98, and the force of oil pressure on the plunger I94. Theplunger, I94is .slightlylarger than the plunger I98 so that the force exerted to tilt the. cam plate'24 will be proportional to the pump discharge pressure; and the relative areas offigthe plungers I94. and I98.v The force ofrth'e spring 2I2 will be almost'constant, but willwar slightly with the degree of compression. V 1 In Fig. 14 weshow amodifiedi arrangementifor the spring 21'2wherein theispring ,is' enclosed within the cylinder; 200%. This Ecylinder. :corre-I sponds ,to---,.th e cylinder 209 .:but is; enlarged E to include the springi2l2 and anadditional spring 2 I 3,. if desired; -.!Ihe springseare;enclosedewitliin the cylinder, rand;- iboth springs are 1; interposed between a head 2I4 on the .plunger-iI98i-and an adjusting plug; 2 I16, The :plug. maylbeg'serewed nwa or outwa dl for i reasin ior decreas ing the pressure; of; ,the springs? I-2 :2 I3, for

r l racticaj lope if Lilsha t H isli rir nwil means to thereby drive thee 81 and the rotor 38 of the low pressure or first-stage pump. Rotation of. the rotor 38 causes liquid to be drawn in from the, intake I I andpassthroughl the-passageway I2 to the intake port 1370i thelow pressure P m t is: quid, b i d sc ar ed through the-outlet port "15 of the low pressure pump into the passageway 16. i The liquid is then, picked up from the intake port H of the high, pressure pump and discharged into its outlet:

port I9, from which it passes throngh the passage waysBIl, the, opening I4 and thepassageway -fll to the pump outlet 82. The.creep plate3flispositioned so that the cylinder ports '58 communicate;

with the port Tl on the intake strokesofjthe pistons '56, and with theport 19 .on theo tlet strokes thereof. The'liq'uid is thus pumped a high pressure from the pump As to the low pressure or sliding vane-hump it pumps liquid at low pressure;-.to charge the high pressure pump, and. is designed to over charge the high pressure pump. Pressure by the low pressure pump, however,;is regulated by the relief valve I12, the excess liquid passing through the passageway I68 to the'interior of the sleeve I60, and there forcing the plunger II 2 upwardly until the liquid pressure overcomes the spring I16, whereuponthe excessliquid is bled through the annular passageway I66 and the: passageway Ill] 'into'the interior of the housing In. The

interior of the housing is maintained at a pre determined pressure between that for which the valve I12 is set and. atmospheric pressurev by the relief valve I42. The by-passe'd oil thusflcircu; lates' through the "housing I9, lubricating. the

working surfaces and finding itsfwayfinto.the

passageway I36, and, finally,.back through the relief valve I42 and the. passageway I 58 to' the pump inlet II. Theliquid issealedfofifrom atmosphere around'the 'drive shaft lln jby 'the sealing arrangement I I6--] I8. 7 f

'By' thefar'rangement just described a substantially even pressure of oil is supplied from the. low-pressure pump [to the high p es urejpum to, assure 'full charging ofthe high pressure, pump. even after the pump be'cpmes worn to ome extent. During starting operation, the spring 59 keeps the barrel 44 in engagement withthe valve plate I6, and :the. springJIZU keeps. thejseal'plate H8 in 'eng'a'gementj'with the flange"! I6 so tha there is a sealed chamber within'the housing I9 allvthe way from the end plate I8 to .the diae. phragm I25. These springs, particularly, the spring 59, maintain the seal necessary for priming the pump. Ther'eis some leakage: of liquid past, thefaces Stand 52, especially before ressure' is built'up in the housing I0, andth fiquid, "together'with the small amount which the pistonsifi and any which-may" lo wpressurepump, willcharge t: boi 9 i iad it i fihegb assedmil 2 thei s e e .1 0, her b ubrica n t e bea ing su aces. 32,334 and. lfiaa-nd prod c n Q 325? re Wi h gt e housin The ba e willghe seat d ain the alvepl te l6. und 'the action of, he harsi pre su r.; he h us g plus.

the n er a r s ur q -t e l nderb r ac in o the-p rtia ly closed..cylindertends.i

. The h u n p e su e. also. acts .onithegfiari H t omp es -.th. sp ing 12.0 som wh and nterior oi the mg 1. "T liqu d testiej-vwiiem n e e va v o a eliet osi ion p rmittin the 9 vcess liquid to fiow through the ports I54, I56 and'I58 back to the low pressure boss H. A se lected spring I46 may be used as required to keep a desired pressure within the housing. The valve [.42 therefore acts as a pressure regulating valve.

Our two-stage pump herein disclosed can be readily adjusted for a reversal in the direction of rotation by turning the end plate I8, and the valve plate I6, 180". This is accomplished by removing the screws 20 and reinserting them after the adjustment has been made.

In the operation of the form of invention shown in Figs. 12 and 13, when. the pump I is at rest the spring 2I2 acts to tilt the cam plate 24 to the maximum displaced position of Fig. 12. As the pump. discharge pressureis built upthe plungers I-94and I98 begin to exert force on the projections I90 and I92, with the plunger I94 exerting a largerforce than the plunger I98 due to their difference in area.

I At the predetermined pressure for which the pump has been designed the force exerted by the plunger I94 is exactly equal to the force exerted by the plunger I98 plus the force of the spring 2 I2. .At any pressure less than this the force of the plunger I94 is less than the additive forces of the plunger I98 and the spring 212. As the pressure increases beyond the value at which these forces are in equilibrium,,,and the cam plate is inmaximum displaced position, the force exerted by the plunger I84 will be larger than the forces exerted by the spring and the plunger I98, thus causing the cam plate to be tilted toward a vertical position. Further increasesin pressure will. finally cause the cam plate to assume a posispring is compressed. In such .a position the displacement of the pump will be proportionally lower than the maximum displacement.

angle slightly less than vertical, and the .displacement of the pump willbe only enough to overcome the slip or volumetric inefficiency of thejpump and whatever othervleakage of high pressure oil occurs. The pressure will be only that much higher than the maximum at Which full displacement occurs as occasioned by the difference in spring force at the minimum compression andat the maximum compression position With the alternate'methcd (Fig. 14') of installing spring means for the regulating func tion just described the action is substantially the same, with the spring exerting. its force through the plunger IBB instead of directly on the cam plate 24. This arrangementhas the additional advantage that the spring force can -be adjusted and, by so doing, the cut-off pressure can be adjusted.

.lirom .the foregoing specification, we believe it will be obvious that we have provided a structure which compactly includes both a, low pres sure pump and a high pressure pump, whereby of the pump. The seal. at I Iii-l I8 remains efv.fec'tive even if the shaft 110 is out of. alignment wardly by centrifugal force, and the volume .35 tion whe're the forces are againin equilibrium,

'since the spring force increases slightly as the 40 ,Ifflthe fiow'through the outlet of the pump' "is reduced to ,zero the cam plate will assume an I pressure operating on both plungers.

trapped between two adjacent blades alternately increases and decreases as the rotor turns, there, by giving the desired pumping action. The inlet and outlet ports I3 and I5 of the l'owpressure pump are preferablyoverlapped slightly at their large ends with respect to the adjacent vanes 58 to insure good filling of the low pressure pump, especially at high rotative speeds.

The hi h pressure pump is preferably provided with a considerable number of pistons to reduce pressure pulsations, and this pump is pressurized by the low pressure pump to elimi- ,nate cavitation therein. The low pressurepump also eliminates the necessity of springs or link- ,age normally used for returning the pistons of the high pressure pump.

The vane pump ports I3 and I5, it will be noted, are axial, to avoid pressure drop experienced with por,ts 'of the, radial entry type. The passageway arrangement from. the inlet I,' I ,to the outlet .82 is reduced to a minimum, thus conducting the liquid in the .most direct path possible to minimize both turbulence and conduit wall friction on the flowing liquid. ,All of the pumping Power transmitted to the rotatin barrel 44 is carried through concentric shafts which are not subjected to any appreciable thrust. Ball bearing arrangements disclosed also contribute to the efiiciency of the pump,...and the series arrangement of the low and high pressure sections of the pump is such that an extremely compact structure results. ,At the same time, the parts are designed rugged enoughfor containing the high pressures generated.

The valve plate I6, carries the outlet port for the low pressure pump. and both the inletand outlet port forthe high pressure pump. Since this plate is fiat on both surfaces it can easily be fabricated, and ground and lapped on its surfaces to insure proper working fit.

With the modified arrangementshown in Figs. 12, .13 and 14 automatic regulation of the output of the pump is had. The trunnion mounting arrangement permits oscillation of the cam plate to the desired control position, and it willfbe noted that the'center line of the trunnion bearings is located coincident with a planethrough the fiat surface of the creep plate 30 against which the high pressure pistons, engage. For such engagement, see Fig. 3. With the arrangement of two opposed plungers I94 and I98, stability of operation is had due to the outlet Proper selection of plunger diameters will allow the use of a spring with a low rate of regulation, so

a complete hydraulic pump suitable for high manner that the necessity of-employing split that zero fiow pressure is only slightly higher than maximumdisplacement pressure. This design also is readily adapted for mechanical or any other type of control, such as the hydraulic control disclosed.

Asimple means of adjusting the cut-off pressure is-included in the alternate arrangement of the spring as shown in Fig. 14. The trunnions I are installed in the sleeves I82 in such construction of the sleeves is obviated.

pSome changes may be made in the construction and arrangement of the parts of our pump structure without departing from the real spirit and purpose of our invention,.and it is our intention to cover by our claims any modified forms of structure or use of mechanical equivalentswhich may be reasonably included within their scope.

We claim as our invention; I ,L In a hydraulic pressure pump of the character'disclos-ed, a housing, a barrel driving shaft journaled in said housing, a barrel mounted on said, driving; shaft sli'dably and non-rotatably relative. thereto, said barrel having cylindrical bores substantially parallel'to the axis of rotation of saidbarreland driving shaft, a piston in each of saidcylindrical ibores, a valve plate at one end of; said barrel, said barrel having lone of its ends seated thereagainst, a cam plate havinga cam surface surrounding said driving shaft and in the shape of a truncated cylinder end, a creep plate interposed betweensaid'cam and said pistons, bearings interposed between said cam plate and said, creep plate, an end plate beyond said valve plate andhaving intake and discharge openings therein, a low pressure vane pump recessed in said end plate and having one face against said valve plate, passageway con- .nections through saidrend plate from said in take opening to said .low pressure pump, said 'valve, plate having inlet and outlet ports for said bores of said barrel, and passageways through said valve plate only from the outlet of saidlowcpressurepump to said inlet port and from, said outlet port to the, discharge opening of-said end plate. 1

, 2'. In ahydraulic pressure pump of .thecharacterdisclosed, a housing, a barrel driving shaft journ'aled insaidhousing, a barrel mounted on said fdriving shaft and operatively connected thereto for rotation therewith and for sliding movement reI'ative'ther-eto, said barrel having cylindrical bores substantiallyvparallel to the plate and having intake 'and dischargejopeni gs axis of rotation of said driving shaft; a piston in ea'ch of said cylindrical bores'ga' valve plate atfone end of said barrel, said barrel having .ofne. of its ends seated thereagainst, a cam having acam surface surrounding said driving shaft and in the shape of a truncated cylinder end, an end plate beyond said valve plate and having intake and discharge openings therein, a low pressure vane pump located in said end plate and.against said valve plate, passageway connections through said end plate from said intake openingto said low pressure pump, saidlvalve plate having inlet and outletports for saidbores of said barrel, and passageways through said valve plate from the outlet of said low pressure pump to said inlet port and from said outlet port to the discharge opening of said end plate.

: -3. Ina hydraulic pressure pump, a housing, a barrel driving shaft journaled in saidhousing,

barrel slidably mounted on said driving shaft.

and operatively connected therewith, said barrel having cylindrical bores, a piston .in each of said 'cylindrical bores, a valve plate at one end of, said barrel, said barrel havingone of its ends seated thereagainst, ports in said valve plate and communicating with said cylinder bores, a cam having a cam surface surrounding said driving shaft and-in the shape of a truncated cylinder'end,

an end plate beyond said valve plate and having 'intake' iand discharge openings therein, and a low pressure vane pump located in said end plate and against said valve plate for pumping fluid I under low pressure to saidcylindrical bores.

shaft and in theshape of atruncated cylinder end, an end plate beyond ,said'valve plateand having intake and diSChal'gQ'QfiflflingSjlibel n, a low pressure vane purnp located insail plate and a passageway through said valv for pumping fluidcunder low fpressure cylindrical bores, and a pressure regulating by,- pass from said low pressure pump to said in said housing surrounding.saidbarrel.

,5. In a hydraulic pressure pump, a housing, a barrel driving shaft journaled in said bru sing, a barrel mounted on said driving shaft and openatively connected therewith, said housing'pror viding a primary space surrounding said barrel, therebeing a secondary. space between saidibarrel and said; driving shaft, saidbarrel havingjcy drical o esfl pi tdnneaqh rsaiipyimauca bores, a valve platefat one end ofsai'd barrel, Said'barrel having ,one ofitslendsjfseatedthe eagainst, intake and exhaust ports in said valve plate .and communicating' with said I cylinder bores, a cam having acamsurface surrounding said driving shaft and in the shape of, a truncated cylinder end,.an end plate beyond saidv, ve

leaks, past said pistons and/or from betweensaidbarrel-and said valve plate, and a pressure regulating byrpass from said secondary space to the intake opening of said end plate. 1

6. In a hydraulic pressurepump, a housing, a barrel driving shaft journaled in said .housi'ng,' a barrel mountedon said driving sh'aftandoper atively connected therewith said housingprovid: ing a primary space surrounding .said'barrel, there being a-secondary space between said barrel and said driving shaft, said barrel having cylindrical bores, a piston in each of saidlcylindrical bores, a valve platev at one end or. said barrel, said barrel havingone of its endsseated thereagainst, intake and exhaustports in said valve plate and communicating with said cylinder bores, ,a cam having a cam surface surrounding said, driving shaft and in thefshape of. a truncated cylinder'end, an end plate beyond said "valve plate and having intake and. discharge openings therein, a low pressure vane pump located' in said end plate andja passageway t ough said valve plate for pumping fluid undeflo'vv pressure to said intake ports, said primary space and said secondary space receiving any fluid that'leaks past said pistons and/or from between" said barrel and'said valve plate jto said cylindrical bores, and a pressure regulating bypass from' said secondary space to said' intake opening of'said end plate. I V

' 7. In a two-stage hydraulic pressure pump,' ,a housing, a shaft journaled in said housing a barrel mounted on said shaft andoperatively, con nectedthereto, saidbarrel having cylindrical bOl'es, a piston in each of said cylindrical bores,

'13 a valve plate atone end'of said barrelfsaid barrel having one of its ends seated thereagainst,,ports sure pump, and passageway connections through said valve plate from said low-pressure pump to 53 said ports in said valve plate and from said ports in said valve plate to said discharge opening of said end plate.

8. In a two-stage hydraulic pressure pump, a housing, a valve plate against one end of said housing, an end plate against said valve plate, a a a low pressure pump located in and faced against said end plate, said end plate having an inlet port therefor, said valve plate having an outlet port for said low pressure pump, a high pressure pump comprising a barrel rotatable in said housing and provided with cylinder bores, pistons in said cylinder bores, said valve plate havinginlet and outlet ports from said cylinder bores and passageways from the outlet port for said low pressure pump to the inlet port for said cylinder bores and from the outlet port for said cylinder bores to said end plate, said end plate having intake and discharge openings in the outer face thereof,

said openings communicating respectively with said inlet port for said low pressure pump and the valve plate passageway from said outlet port for said cylinder bores.

9. A two-stage hydraulic pressure pump comprising a housing, a valve plate against one end of said housing, an end plate against saidvalve plate, a low pressure pump recessed in said end plate and having one face thereof coincident with a face of said valve plate, said end plate having an inlet port therefor, said valve plate having an outlet port for said low pressure pump, a high pressure pump comprising a barrel rotatable in said housing and provided with cylinder bores, pistons in said cylinder bores, cam means to reciprocate said pistons, said valve plate having inlet and outlet ports from said cylinder bores and passageways directly from the outlet port for said low pressure pump to the inlet port for said cylinder bores and from the outlet port for said cylinder bores to said end plate, said end plate having in its outer face intake and discharge openings communicating respectively with said inlet port for said low pressure pump and the valve plate, passageway from said outlet port for said cylinder bores.

10. In a pump structure, a housing, a valve 7 plate at one end thereof, an end plate against said valve plate, a shaft journaled in said housing and said valve and end plates, a low pressure pump rotor on said shaft within said end plate, one face of said rotor being against said valve plate, a high pressure pump barrel on said shaft within said housing, said barrel having a plurality of high pressure cylinders, a piston in each of said cylinders, an annular cam for reciprocating said pistons upon rotation of said shaft, said barrel having an outlet port for each of said cylinder bores, said end plate having an intake opening and a discharge opening, said valve plate having an outlet port for said low-pressure pump and. inlet and"outlet "ports. for :said highpressur'epump, said end plate having an inlet port forvsa'id low=pressure pump, and-passageway connections in said valve :plate and'sa-id-tend plate from rsaidintakeopening to said inlet :port for said low-pressure pump, from the outlet port for saidilow-pressurie pump to the'iinlet portfor saidhigh-pressure. pump, and from "the :outlet port for said high-pressure pump to said "discharge opening' 1=1-.' I'n-'a pump structure, a housing, a recessed end pl'a'te at one end thereof, the bottom of said recess constituting a face of said end plate, a valve plate interposed between"said housing and said :end plate, a shaft, a, low pressure pump rotor on said shaft within the recess-pf saidend plate, said rotor being substantially so thick as the depth of said recess, a high pressure pump barrel on said shaft within said housing, said barrel having a plurality of high pressure cylinders, a piston in each of said cylinders, an annular cam for reciprocating said pistons upon rotation of said shaft, said barrel having an outlet port for each of said cylinder bores, said end plate hav-.- ing anintake opening and a discharge opening, said valve plate having an outlet port for said low-pressure pump and. inlet and outlet ports for said high-pressure pump, said end plate having an inlet port for said low-pressure pump and passageway connections from face to face of said end plate from said intake opening to said inlet port for said low-pressure pump, from face to face of said valve plate from said outlet port for said low-pressure pump to said inlet port for said high-pressure pump, and from face to face through said valve plate and said end plate in series from said outlet port for said high pressure pump to said discharge opening. I

12. In a pump structure, a housing, a valve plate at one end thereof, a recessed end plate against said valve plate, a shaft journaled in said housing and said valve and end plates, a low pressure pump rotor on said shaft within the recess of said end plate and faced against said valve plate, a high pressure pump on said shaft within said housing, said end plate having an intake opening and a discharge opening, said valve plate having an outlet port on one side for said lowpressure pump and inlet and outlet ports on the. other side for said high-pressure pump, said end plate having an inlet port for said low-pressure pump, passageway connections in said valve plate and said end plate from face to face thereof and leading from said intake opening to said inlet port for said low-pressure pump, from said outlet port for said low-pressure pump to said inlet port for said high-pressure pump and from said outlet port for said high-pressure pump to said discharge opening, a pressure regulating valve between said low and high pressure pumps, and a pressure relief valve between said low pressure pump and said intake opening.

13. In a pump structure, a housing, a valve plate at one end thereof, a recessed end plate against said valve plate, a shaft journaled in said housing and said valve and end plates, a low pressure pump rotor on said shaft within the recess of said end plate, said rotor having one face thereof contacting said valve plate, a high pressure pump on said shaft within said housing, said end plate having an intake opening and a discharge opening, said valve plate having an outlet port for said low-pressure pump on one side and inlet and outlet ports on the other side for said high-pressure pump said end plate having=an inletlport for 'said' low-pressure pump.

passageway connections from face to face of said valve plate and said endplate leading from said intake opening to said inlet port for said low- .pressui'e pump, from said outlet port for said low-pressure pump (to said inlet port for said high-pressure pump, and from,.said outlet port for said high=pressures pump :to said discharge opening. V q

BERNARD BEAMAN.

- JULIUS ROBERT A. STEIN.

,R-EFEBENCES' CITED- Thefollowing references are of feoord in the slew this patent: v 2 2 Number Beaman et a1. Jan. 31, 1950 

